The belt conveyor, due to its safe, reliable operation and adaptability, has been extensively adopted by industry. Example uses include transporting raw materials and/or inputs to production processes. Belt conveyers have many applications such as mining, metallurgy, manufacturing and power production to name a few.
Like most mechanical items, conveyor belts can wear out and eventually break. Excessive wear or breakage of a conveyor belt continuously damaged can cause considerable economic loss. A severely damaged belt can damage the structural platform, the engine, motor or devices associated with it or even cause physical injuries to workers.
To make sure efficient use is made of a belt conveyor, it is possible to monitor its structural integrity by measuring and verifying the reduction of belt thickness due to wear during operation. Many such belts are reinforced with steel cords or woven fabric but rely on rubber material for structural integrity. Periodic inspection of rubber cover layers is typically made along the length of the belt by performing manual thickness measurements using an ultrasonic probe.
To perform such manual measurements, it is generally necessary to stop the belt conveyor. Such manual thickness measurements are often directed to so-called rubber “cover regions” that for example cover internal woven fabric or steel cord reinforcing elements within the belt. The techniques currently employed make point thickness measurements (e.g., from 15 to 18 points in the transverse direction of the belt every 50 or 100 meters in the longitudinal direction). The rubber cover region of the belt may for example have a nominal thickness of between 12 to 14 mm. A belt region with the most wear is likely to be the center of the belt where there is or can be charge buildup. Such manual measurements if performed periodically can often detect belt wear before failure occurs.
In more detail, FIG. 1 shows a cross-sectional view of an example steel reinforced rubber conveyor belt 10. Belt 10 includes a rubber cover region 12, a steel cord (or other reinforcement) region 14, and a rubber return region 16. In current techniques, the belt 10 is stopped and an ultrasonic sensing probe 18 is manually placed on the surface 20 of the rubber return region 16. The ultrasonic sensing probe 18 emits high frequency audio pulses which pass through the rubber cover region 12, are reflected by the steel wires region 14 within the belt, and return to the sensor 18. The sensing probe 18 or its associated equipment measures the ultrasonic pulse propagation delay time (i.e., by comparing the time the pulse was emitted to the time it returns) to determine the thickness of cover region 12. Longer delay times indicate a thicker cover region 12, while shorter delay times indicate a thinner cover region. Well known calculations based on sound propagation delay through different materials can derive a precise thickness measurement from such techniques. The ultrasonic measurement is repeated at various point positions spaced at intervals along the belt 10 to detect the thinnest part of the belt cover region 12. See for example http://www.olympus-ims.com/en/applications/thickness-testing-rubber-conveyor-belt/.
If the thickness of the rubber cover region 12 is near “zero” mm thickness (i.e., the steel cords 14 are nearly exposed), there is a risk of accidents (e.g., belt rupture) due to lower resulting belt tensile strength. Measurements are often taken periodically to determine the optimum time to stop the equipment for belt replacement. The best time to replace a belt may be at a time that minimizes the risk of rupture but seeks to maximize use of the asset.
Typically, the industry replaces a belt when the cover region 12 has worn to a thickness of 1 mm thick or less. Removing a belt having 2 or 3 mm of remaining rubber cover region 12 might mean underusing the asset. Replacing a belt more often than necessary halts the production or conveyance line a greater number of stops for exchanging belts—leading to possible impacts in production objectives and efficiency, depending on when replacement occurs.
Improved efficacy in predicting the time to stop and measure and/or replace the belt, and better measurement accuracy, can lead to decreased cost impact on the industry and other advantages.